The ecological importance of clean air is as evident as our need to breathe. Nevertheless, the demands of an industrialized society and the consequent burning of fuel for energy tends to compromise air quality. Existing fuels that are burned in boiler systems to produce steam for heating and power supply include distillate (number 2) fuel oil, residual (number 6) fuel oil, blended distillate and residual fuel oil, and coal. These fuels typically release substantial quantities of harmful pollutants, such as sulfur oxides, nitrogen oxides and carbon monoxide. Moreover, each of these fuels is subject to supply shortages as societal energy demands increase. In fact, dwindling mineral oil reserves are a primary factor in the ongoing energy-supply crisis.
Clean air legislation, such as the Clean Air Act in the United States, has been enacted to control the amount of various chemicals released into the atmosphere in an effort to protect human health and the environment. At a local or regional level, industry is typically regulated by state environmental protection agencies that set limits as to the amounts of airborne pollutants that can be emitted from a given facility.
Many existing energy sources, particularly mineral oils (e.g., petroleum-based fuels), release substantial amounts of pollutants, such as nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO) and particulate matter (PM) upon burning. These pollutants cause respiratory diseases, other human ailments and, over time, death. These pollutants also poison the environment via acid rain, ground-level ozone and greenhouse-gas-induced global warning.
As energy demands increase, the pressures, conflicts and costs involved in supplying that energy without exacerbating these health and environmental problems and in complying with clean air regulations become increasingly pressing.